Wendigo

The Wendigo staring down at a camera left behind by its most recent victim.

A Wendigo is featured in The Monster Attacks 2. In Native American mythology, it's a spirit that possesses humans and turns them into cannibals. In the novel, the Wendigo is a result of college student Petra Williams being bitten by a dog infected with the Rage Virus. The Wendigo is considered by several characters to be the "scariest monster to exist."

The Wendigo is at first an unknown girl that has been infected by the Wendigo virus. However, after his initial encounter with the creature, Nathan Lynn discovers the creature used to be a college student named Petra Williams from Charleston, West Virginia after stumbling upon a trashed campsite (which belongs to the lost campers). To his horror, Nathan finds diary entries and a series of videos from a movie camera camera he found in the woods from April 14, 2012 containing extremely graphic events leading up to Petra's transformation into a Wendigo.
Petra, now a Wendigo, starts chasing her friends through the woods and pursues Abby Burr's sister Cassie into a cave. From there, it begins to kill off various people one by one; it later becomes disinfected, reverting Petra back to human form.

In addition, a second Wendigo appears in northern Canada. The Russian President, Petya Puskov, ends up trapped in the forests of northern Canada after Taliban terrorists attempt to hijack his plane, causing it to crash into northern Canada. The FSO manages to kill off the Taliban hiding in the woods, but they soon realize they are being hunted; fellow Monster Investigations Incorporated agent Korey Hogan is sent in with a team of US Marines in order to find out what happened, but are hunted by a Wendigo. He also learns the history behind the Wendigo assaults and works with the agents to stop the killings from escalating again, resulting in a cat-and-mouse chase through the Northern Canadian woods, which eventually leads to Korey destroying the creature, but not before it kills him first (it's unknown weither the President was found).

Originally, the Wendigo was supposed to be a guy throughout the entire novel.

Cassie was also supposed to be killed by the Wendigo, but this was changed.

Cassie is the soul survivor of the whole incident, other than Jared, Nathan, Nikki, a handful of the campers, and Dimitri.

The Wendigo was orginially going to be just a crazed human instead of a creature with a deer skull for a head.

The attacks on Nathan Lynn, Nikki Harding and the murdering of the entire SWAT team and half of the entire GRU are the only attacks that happen in broad daylight. The other assaults occur at night.

The Wendigo was originally supposed to kill Dimitri Mayakov, but this was changed.

The new Wendigo, unlike the first, looks different. The new one is a guy, but wears a deer skull too and wields a variety of bladed weapons.

There are two Wendigo types: one is the partial animal type as depicted in The Monster Attacks 2, in which the Wendigo still retains human emotion, though it kills and eats other humans, and the other is the whole (full) animal type, in the human acts like an animal entirely.

The Wendigo that is in the epilogue and in Northern Canada is the full animal type.

The second heart's durability varies from type; the second heart in the partial-animal is moderate, as destroying it with anything ranging from assault rifles to submachine guns will destroy the entire virus infecting the human. The full animal's second heart is much harder; it takes from six to seven hits from a high-power gun to destroy it.

Both the American and Canadian Wendigo, though they vary by type, are the same in appearance; they're cannibals that have deer skulls for heads in order to "hide their elusive and terrifying appearance."

The American and Canadian Wendigos are look-alikes; their differences lie in their behavior.